What is the right way to clear Flash Session?

I'm outputing flashSession in my View using this method - flashSession.output(). When i reload the page the flash messages are still there. How can i remove them in a right way?
Sequence like this does not work:
flashSession.output().
flashSession.clear().

@paul, thank you for your answer. I have the same error but I didn't see any solution. My project is huge. This is not coded by mine. So, there are many flash.output using. I can not try this way. Now, I used flashSession->clear, flashSession->getMessages(false) and flashSession->setAutoScape(false) methods. Now I have a very interesting and difficult the explain error. I hope I will solve. Thanks again!